Decimal	Hex	Binary	4-bit signed
0	0	0000	0
1	1	0001	1
2	2	0010	2
3	3	0011	3
4	4	0100	4
5	5	0101	5
6	6	0110	6
7	7	0111	7
8	8	1000	-8
9	9	1001	-7
10	A	1010	-6
11	B	1011	-5
12	C	1100	-4
13	D	1101	-3
14	E	1110	-2
15	F	1111	-1